In recent years, the merger of the automobile with electronics has been responsible for improvements in automobile safety, operability, comfort, reliability, low fuel consumption, cleaner exhaust gas, reduced noise, navigation, radio/TV, and heating/cooling systems. In order to take advantage of all of these improvements, the number of wires required inside of an automobile has increased manyfold. This, in turn, has caused industry to seek lighter and thinner wires. But the crowding of these wires in small spaces within the automobile, even though the wires are lighter in weight and thinner in diameter, raises the problem of abrasion caused by rubbing against each other and against parts of the automobile. The abrasion is further aggravated by the various vibrations, which arise when an automobile is in use.
In addition to the problem of abrasion, automobile wires have to be resistant to heat, low temperature, humidity, oil, and the whitening caused by carbon dioxide. They also should be flame retardant.
Polyvinyl chloride (PVC) has been suggested as a coating for automobile wires, but because of the plasticizers used in PVC, there is a tendency for the coating to bleed. This can lead to sticky surfaces of both the wires and the parts with which the wires come into contact, and repair problems. Burning of PVC also leads to the evolution of harmful gases.
As a substitute for PVC, polyethylene together with a filler such as magnesium hydroxide or aluminum hydroxide has also been suggested as a coating for automobile wires. While these coatings do not contain halogens or plasticizers, they have been found to be susceptible to abrasion and whitening.
It would be desirable to provide a coated automobile wire, which, in addition to having the positive properties of PVC coated wire and wire coated with magnesium hydroxide or aluminum hydroxide filled polyethylene, does not contain halogens or plasticizers, and does not suffer from the problem of abrasion or whitening.